Process for preparing N,N&#39;-difluorodiazoniabicycloalkane salt, intermediate therefor

ABSTRACT

A process for preparing a N,N&#39;-difluorodiazoniabicycloalkane salt of the formula: ##STR1## by reacting a corresponding diazabicycloalkane or diazabicycloalkane Br.o slashed.nsted acid salt and fluorine in the presence of a Br.o slashed.nsted acid or in the presene or absence of a base, by reacting a corresponding N,N&#39;-difluorodiazoniabicycloalkane salt and an acid or salt, by reacting a corresponding diazabicycloalkane and fluorine in the presence of a Br.o slashed.nsted acid and then reacting an intermediate product and an acid or salt, or by reacting a corresponding diazabicycloalkane Br.o slashed.nsted acid salt and fluorine in the presence or absence of a base and then reacting an intermediate product and an acid or salt.

This application is a 371 of PCT/JP96/02183, filed Aug. 2, 1996.

FIELD OF THE INVENTION

The present invention relates to a process for preparing aN,N'-difluorodiazoniabicycloalkane salt, an intermediate useful forsynthesizing such the salt, a product and use of the product.

The N,N'-difluorodiazoniabicycloalkane salts are useful as anelectrophilic fluorinating agent for organic compounds (see U.S. Pat.No. 5,367,071, EP-A-0 657 457 and JP-A-7-233167).

PRIOR ART

The following processes have been developed for the preparation of theN,N'-difluorodiazoniabicycloalkane salts:

(1) A 1-hydro-4-aza-1-azoniabicycloalkane salt is fluorinated withfluorine (F₂) in the presence of an alkali metal salt (LiOSO₂ CF₃) (seeU.S. Pat. No. 5,367,071);

(2) A 1,4-diazabicycloalkane is reacted with a twice molar amount of aLewis acid (BF₃, PF₅ or SO₃), and then fluorinated with F₂ (see EP-A-0657 457, Examples 3, 4 and 5);

(3) A 1,4-diazabicycloalkane is reacted with an equimolar amount of aLewis acid (BF₃), followed by fluorination with F₂ in the presence of analkali metal salt (NaBF₄) and a monofluorinated intermediate isobtained. Then, this intermediate is treated with 100% F₂ in a sealedreactor under reduced pressure (20 mmHg) (see EP-A-0 657 457, Examples 1and 2).

(4) A 1,4-diazabicycloalkane is reacted with a trialkylsilylester (Me₃SiOSO₂ CF₃), followed by fluorination with F₂ (see EP-A-0 657 457,Example 6).

(5) A 1,4-diazabicycloalkane-monotrifluoroborane is reacted withperfluorobutyl chloride in the presence of NaBF₄ and1-perfluorobutyl-1,4-diazoniabicycloalkane-trifluoroboranetetrafluoroborate is obtained. Then, this tetrafluoroborate isfluorinated with F₂ in the presence of NaBF₄ (see EP-A-0 657 457,Example 7).

However, these recently developed processes are not industriallyadvantageous processes since they have the following material drawbacks:

In the process (1), the product is obtained as a mixture with theunreacted raw materials, and a metal fluoride which is another productof the reaction induces the decomposition of the desired product.Therefore, it is difficult to isolate the desired product in the pureform. Furthermore, it is difficult to remove the insoluble metal saltfrom the product having the low solubility.

In the process (2), a large amount of the solvent is necessary, forexample, 25 ml of CH₃ CN per 1 mmol of the diazabicycloalkane, inparticular when a N,N'-difluorodiazoniabicycloalkanebis(tetrafluoroborate) which is a useful fluorinating agent is prepared.The yield of the product is low. Furthermore, the product is obtained asa mixture of the raw material, its monofluoride and the desired productand the obtained mixture is a hygroscopic solid and decomposes throughmoisture absorption. Therefore, the purification of the product isimpossible.

The process (3) is highly dangerous since fluorination is carried out ina sealed reactor under reduced pressure (F₂ pressure of 20 mmHg) withcontacting extremely dangerous 100% F₂ gas, which may ignite and explodewhen it comes in contact with the organic solvent around atmosphericpressure to increase the yield, to the reaction solution in the organicsolvent.

The process (4) uses the expensive trialkylsilyl ester, and is alsodangerous since a large amount of volatile trialkylsilyl fluoride whichis generated as a by-product reacts with F₂ vigorously and may explode.

The process (5) must use the expensive perfluoroalkanoyl fluoride, andrequires a large amount of the solvent like the process (2). The yieldis low. Furthermore, the product after post-treatment is a mixture ofthe monofluoride and the desired product in a ratio of 7:10, andtherefore, the purification of the product is difficult.

SUMMARY OF THE INVENTION

As the result of diligent studies for solving the above problems, anovel process has been found which can prepare a desired product of highpurity by fluorinating a diazabicycloalkane in the presence of a Br.oslashed.nsted acid, and if necessary treating the product with an acidand the like, and the present invention has been completed.

That is, the objects of the present invention are to solve the abovedescribed problems, and to provide a process for easily preparing aN,N'-difluorodiazoniabicycloalkane salt of high purity, which is auseful fluorinating agent, from a cheap raw material in a high yield, auseful intermediate for the synthesis of said salt, a desired productand use of the desired product.

In a broad sense, the present invention provides a process for preparinga N,N'-difluorodiazoniabicycloalkane salt of the formula (I): ##STR2##wherein R¹, R², R³, R⁴ and R⁵ represent independent of each other ahydrogen atom, a C₁ -C₆ alkyl group, an aryl group, a C₁ -C₆ alkylgroup-substituted aryl group or an aryl group-substituted C₁ -C₆ alkylgroup, (X¹)⁻ and (X²)⁻ represent independent of each other a conjugatedbase of a Br.o slashed.nsted acid or together form a single conjugatedbase of a Br.o slashed.nsted acid, and n is 0, 1 or 2.

The above aryl group is preferably a C₆ -C₁₀ aryl group.

DETAILED DESCRIPTION OF THE INVENTION

In the first embodiment of the present invention, aN,N'-difluorodiazoniabicycloalkane salt of the formula (I) is preparedby reacting fluorine (F₂) and a diazabicycloalkane of the formula (II):##STR3## wherein R¹, R², R³, R⁴, R⁵ and n are the same as defined above,in the presence of a Br.o slashed.nsted acid.

The diazabicycloalkane of the formula (II) may be a known compound andreadily available or easily prepared by an analogous method to those forthe preparation of the known compounds (see JP-A-6-25247 and U.S. Pat.No. 5,086,178).

In particular, the compound of the formula (II) in which R¹, R², R³, R⁴and R⁵ are all hydrogen atoms and n is 0 (1,4-diazabicyclo 2.2.2!octane)is commercially produced and sold under the trade name of DABCO(available from Air Products and Chemicals, Inc.) and the like for thepreparation of polyurethane foams, elastomers, epoxy resins,polyacrylonitrile, polyethylene, and their analogous materials.

The above process of the present invention is characterized in that thefluorination reaction is carried out in the presence of a Br.oslashed.nsted acid.

When the N,N'-difluorodiazoniabicycloalkane salt of the formula (I) inwhich the anions (X¹)⁻ and (X²)⁻ are the same anion is prepared, an acidis used, while when the anions (X¹)⁻ and (X²)⁻ are different, at leastone acid is used.

Preferred Br.o slashed.nsted acids are those having the acidity equal toor larger than that of trifluoroethanol known as a weak acid (having anacid dissociation constant pKa of 12.4. see J. Org. Chem., 32, 1217(1967)). Br.o slashed.nsted acids having pKa equal to or smaller thanpKa of acetic acid, that is, 4.6 are more preferable for performing thereaction in a good yield.

Preferable examples of the Br.o slashed.nsted acid having pKa in therange between about 12.4 and 4.6 are halogenated alcohols (e.g.trifluoroethanol, chlorodifluoroethanol, dichlorofluoroethanol,trichloroethanol, tetrafluoropropanol, pentafluoropropanol,hexafluoroisopropanol, octafluoropentanol, hexafluoro-t-butanol,chlorooctafluoro-t-butanol, etc.), halogen-oxoacids (e.g. hypochlorousacid, hypobromous acid, hypoiodous acid, etc.), boric acid, carbonicacid, silicic acid, and the like.

Many known inorganic and organic acids are exemplified as the Br.oslashed.nsted acids having pKa of 4.6 or less. Preferable examples arehydrogen halides; oxoacids of phosphorus (e.g. phosphoric acid,metaphosphoric acid, pyrophosphoric acid, diphosphoric acid,triphosphoric acid, tetraphosphoric acid, polyphosphoric acid,phosphorous acid, hypophosphorous acid, etc.); oxoacids of nitrogen(e.g. nitric acid, nitrous acid, etc.); oxoacids of sulfur (e.g.sulfuric acid, sulfurous acid, thiosulfuric acid, dithionic acid,pyrosulfuric acid, disulfuric acid, polythionic acid, etc.); oxoacids ofselenium or tellurium (e.g. selenic acid, selenious acid, tellurousacid, etc.); halosulfonic acids (e.g. fluorosulfonic acid,chlorosulfonic acid, etc.); monoalkylsulfuric acids (e.g.monomethylsulfuric acid, monoethylsulfuric acid, etc.); alkanesulfonicacids (e.g. methanesulfonic acid, ethanesulfonic acid, propanesulfonicacid, butanesulfonic acid, etc.); haloalkanesulfonic acids (e.g.trifluoromethanesulfonic acid, difluoromethanesulfonic acid,trichloromethanesulfonic acid, trifluoroethanesulfonic acid,nonafluorobutanesulfonic acid, etc.); alkane- or haloalkanedisulfonicacids (e.g. methanedisulfonic acid, ethanedisulfonic acid,tetrefluoroethanedisulfonic acid, propanedisulfonic acid,butanedisulfonic acid, perfluorobutanedisulfonic acid, etc.);arenesulfonic acid (e.g. benzenesulfonic acid,pentafluorobenzenesulfonic acid, toluenesulfonic acid,nitrobenzenesulfonic acid, dinitrobenzenesulfonic acid,bromobenzenesulfonic acid, etc.); arenedisulfonic acids (e.g.benzenedisulfonic acid, naphthalenedisulfonic acid, etc.); alkanoic orhaloalkanoic acids (e.g. formic acid, acetic acid, propionic acid,trifluoroacetic acid, trichloroacetic acid, pentafluoropropionic acid,etc.); oxalic acid; alkane- or haloalkanedicarboxylic acids (e.g.methanedicarboxylic acid, ethanedicarboxylic acid, propanedicarboxylicacid, tetrafluoroethanedicarboxylic acid, perfluoropropanedicarboxylicacid, perfluorobutanedicarboxylic acid, etc.); alkanediphosphonic acids(e.g. methanediphosphonic acid, etc.), compounds comprising hydrogenhalides and Lewis acids (e.g. HBF₄, HBCl₄, HBCl₃ F, HB₂ F₇, HAlF₄,HAlCl₄, HAlCl₃ F, HAsF₄, HAsF₆, HAsCl₃ F, HAs₂ F₁₁, HPF₄, HPF₆, HSbF₄,HSbCl₄, HSbF₆, HSbCl₅ F, HSbCl₆, HSb₂ F₇ HSb₂ F₁₁, HSiF₅, H₂ SiF₆,H(CF₃)₃ BF, H(C₆ H₂ F₃)₃ BF, H(C₆ F₅)BF, HNbF₆, HTaF₆, HTeF₇, HTiF₅,HVF₆, HZrF₅, etc.); oxoacids of halogens (e.g. HClO₃, HClO₄, HBrO₄,HlO₃, HlO₄, etc.); tetraarylboric acids, (e.g. tetradi(trifluoromethyl)phenyl!boric acid, etc.); and the like.

Among the above exemplified Br.o slashed.nsted acids, those having pKasmaller than pKa of hydrogen fluoride (HF), that is, 3.17 areparticularly preferable for preparing the highly pureN,N'-difluorodiazoniabicycloalkane salt of the formula (I) in a highyield.

The Br.o slashed.nsted acid used in the present invention may be used inthe form of a complex with ethers (e.g. diethyl ether, dibutyl ether,t-butyl methyl ether, dimethyl ether, etc.); sulfides (e.g. dimethylsulfide, diethyl sulfide, etc.); water; alcohols (e.g. methanol,ethanol, propanol, etc.); nitriles (e.g. acetonitrile, propionitrile,etc.); carboxylic acids (e.g. formic acid, acetic acid, etc.); and thelike. The Br.o slashed.nsted acid may be used in the form of an aqueoussolution.

When the Br.o slashed.nsted acid is a monobasic one, the amount of theacid is at least 0.9 mole per 1 mole of the diazabicycloalkane of theformula (II). Preferably, the amount of the Br.o slashed.nsted acid isat least 1 mole, more preferably at least 1.5 moles in view of theyield. When the acid dissociation constant pKa is 4.6 or less, theamount of the Br.o slashed.nsted acid is between 0.9 and 5 moles, morepreferably between 1 and 3 moles in view of the yield or costs. Forperforming the reaction at high efficiency and yield, the amount of theBr.o slashed.nsted acid is preferably between 1.5 and 2.5 moles, inparticular between 1.8 and 2.2 moles.

When the Br.o slashed.nsted acid is a dibasic one, the amount of theacid is at least 0.45 mole per 1 mole of the diazabicycloalkane of theformula (II). Preferably, the amount of the Br.o slashed.nsted acid isat least 0.5 moles to obtain the product in the high yield. When theacid dissociation constant pKa is 4.6 or less, the amount of the Br.oslashed.nsted acid is between 0.45 and 5 moles, more preferably between0.5 and 3 moles in view of the yield or costs. For performing thereaction at high efficiency and yield, the amount of the Br.oslashed.nsted acid is preferably between 0.75 and 2.5 moles, inparticular between 0.9 and 2.2 moles.

When the N,N'-difluorodiazoniabicycloalkane salt of the formula (I) inwhich (X¹)⁻ and (X²)⁻ together form a single conjugated base of a Br.oslashed.nsted acid is prepared, the amount of the dibasic acid ispreferably in the range between 0.75 and 1.3 moles, more preferablybetween 0.9 and 1.2 moles per 1 mole of the diazabicycloalkane of theformula (II).

The Br.o slashed.nsted acid may be used also as a solvent for thereaction as explained below when it is a relatively weak liquid acid,for example, the halogenated alcohols such as trifluoroethanol,trichloroethanol, pentafluoropropanol, hexafluoroisopropanol,tetrafluoropropanol, nonafluoro-t-butanol, etc.; hydrogen fluoride; orthe alkanoic- or haloalkanoic acids such as formic acid, acetic acid,trifluoroacetic acid, etc.

The fluorine (F₂) used in the present invention is in general a fluorinegas. While the fluorine gas may be used without dilution, in general, itis preferable to use the fluorine gas diluted with an inert gas so thatthe volume of the inert gas is between 99.9% and 50% for controlling thevigorous reaction.

The inert gas may be nitrogen, helium, argon gas, etc.

In general, the reaction proceeds with blowing the fluorine gas ordiluted fluorine gas in or on the reaction mixture. The reaction gas maybe circulated for increasing the reaction efficiency. Alternatively, thereaction may proceed with supplying the fluorine gas or diluted fluorinegas in the reactor under subatmospheric pressure.

The amount of the fluorine may not be uniformly determined since itvaries with the introduction manner, reaction solvent, reactiontemperature, reactor, and the like, but can be easily determined by aperson skilled in the art with aiming at an amount required for theabsorption of the fluorine to substantially cease.

The reaction in the process of the present invention is preferablycarried out in a solvent.

Preferred examples of the solvent are C₂ -C₅ nitriles (e.g.acetonitrile, propionitrile, butyronitrile, isobutyronitrile,valeronitrile, isovaleronitrile, etc.); C₁ -C₈ halohydrocarbons (e.g.methylene chloride, chloroform, carbon tetrachloride,chlorotrifluoromethane, bromotrifluoromethane, dichloroethane,tetrachloroethane, tetrafluoroethane, chlorotrifluoroethane,trichlorotrifluoroethane, perfluorobutane, perfluorohexane,perfluorooctane, etc.); water; C₁ -C₅ alcohols or halogenated alcohols(e.g. methanol, ethanol, propanol, isopropanol, butanol, isobutanol,sec.-butanol, t-butanol, trifluoroethanol, trichloroethanol,hexafluoroisopropanol, pentafluoropropanol, tetrafluoropropanol,hexafluorobutanol, nonafluoro-t-butanol, octafluoropentanol,nonafluoropentanol, etc.); hydrogen fluoride; phosphoric acid; C₁ -C₄alkanoic or haloalkanoic acids (e.g. formic acid, acetic acid, propionicacid, butanoic acid, trifluoroacetic acid, pentafluoropropionic acid,heptafluorobutanoic acid, etc.); and mixtures thereof.

Among them, the C₂ -C₅ nitriles, C₁ -C₅ halogenated alcohols, C₁ -C₄alkanoic acids or haloalkanoic acids or their mixtures are preferablefor performing the reaction effectively and obtaining the product in thehigh yield.

The reaction temperature is usually in the range between about -100° C.and about +80° C. Preferably, the reaction temperature is in the rangebetween -80° C. and +50° C. for performing the reaction at the highyield of the product.

When the amount of the Br.o slashed.nsted acid is less than 2 moles per1 mole of the diazabicycloalkane of the formula (II), it may bepreferable in some cases to supplement the acid in the reaction liquidor mixture after the reaction step so that the total amount of the acidused in the reaction and the supplemented acid becomes 2 moles or morefor improving the stability of the producedN,N'-difluorodiazoniabicycloalkane salt of the formula (I) or increasingthe yield after isolation and purification.

When the used Br.o slashed.nsted acid is a dibasic one and therefore theN,N'-difluorodiazoniabicycloalkane salt of the formula (I) in which(X¹)⁻ and (X²)⁻ together form the single conjugated base of the Br.oslashed.nsted acid is prepared, and the amount of the acid used in thereaction step is less than 1 mole, it is preferable to supplement theacid in the reaction liquid or mixture after the reaction step so thatthe total amount of the acid used in the reaction step and thesupplemented acid becomes 1 mole or more or at most 1.1 moles.

After the supplement of the acid, the reaction mixture is posttreated byany conventional method.

In the second embodiment of the present invention, aN,N'-difluorodiazoniabicycloalkane salt of the formula (I) is preparedby reacting fluorine and a Br.o slashed.nsted acid salt of adiazabicycloalkane of the formula (III): ##STR4## wherein R¹, R², R³,R⁴, R⁵, n and (X¹)⁻ are the same as defined above, in the presence orabsence of a Br.o slashed.nsted acid.

The Br.o slashed.nsted acid salt of the diazabicycloalkane of theformula (III) used as the starting material in the above reaction isreadily prepared by mixing the diazabicycloalkane of the formula (II)and an equimolar amount of the above Br.o slashed.nsted acid.

When the compound of the formula (I) in which (X¹)⁻ and (X²)⁻independently represent the same or different conjugated bases of theBr.o slashed.nsted acids is prepared, the above reaction is preferablycarried out in the presence of the Br.o slashed.nsted acid. When thecompound of the formula (I) in which (X²)⁻ is a fluoride or HF-addedfluoride ion, the above reaction is preferably carried out in theabsence of the Br.o slashed.nsted acid. When the Br.o slashed.nsted acidis used in this reaction, it may be the same as those exemplified above.

When the use of the Br.o slashed.nsted acid is preferable, the amount ofthe acid is at least 0.5 mole per 1 mole of the Br.o slashed.nsted acidsalt of diazabicycloalkane of the formula (III). When the aciddissociation constant pKa is 4.6 or less, the amount of the acid ispreferably between 0.5 and 2 moles in view of the yield and costs. Theamount of the acid is more preferably between 0.5 and 1.5 moles, inparticular between 0.8 and 1.2 moles for performing the reaction at highefficiency and high yield.

The above reaction is preferably carried out in the absence of the Br.oslashed.nsted acid, when (X¹)⁻ in the formula (III) used as the startingmaterial in the above reaction is a conjugated base (HA⁻) of a dibasicacid (H₂ A) in the first dissociation state and (X¹)⁻ and (X²)⁻ in theproduct of the formula (I) together form a conjugated base (A²⁻) of thedibasic acid in the second dissociation state.

The form of fluorine (F₂) used in this reaction is the same as thatdescribed above. The preferable solvent and reaction temperatureemployed in this reaction are the same as those described above.

In the third embodiment of the present invention, aN,N'-difluorodiazoniabicycloalkane salt of the formula (I) is preparedby reacting fluorine (F₂) and a Br.o slashed.nsted acid salt of adiazabicycloalkane of the formula (IV): ##STR5## wherein R¹, R², R³, R⁴,R⁵, n, (X¹)⁻ and (X²)⁻ are the same as defined above, in the presence orabsence of a base.

The Br.o slashed.nsted acid salt of a diazabicycloalkane of the formula(IV) used in the above reaction can be easily prepared by mixing thediazabicycloalkane of the formula (II) and at least one of the abovedescribed Br.o slashed.nsted acid.

The base used in this reaction may be the diazabicycloalkane of theformula (II) or a base which is conventionally used in organicchemistry. To obtain the desired product in the high yield andefficiency, a base from which a by-product soluble in a solvent isderived in the reaction with the fluorine (F₂) is preferably used.Examples of such the base are amines (e.g. ammonia, methylamine,dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine,benzylamine, benzyltrimethylamine, 1,4-diazabicyclo 2.2.2!octane, etc.);ammonium compounds (e.g. ammonium hydroxide, ammonium carbonate,tetramethylammonium hydroxide, tetrabutylammonium hydroxide,benzyltrimethylammonium hydroxide, tetramethylammonium carbonate,tetraethylammonium carbonate, tetrabutylammonium carbonate,tetramethylammonium fluoride, tetramethylammonium fluoride hydrate,tetraethylammonium fluoride, tetraethylammonium fluoride hydrate,tetrabutylammonium fluoride, terabutylammonium fluoride hydrate,tetramethylammonium formate, teraethylammonium acetate,tetraethylammonium acetate hydrate, tetrabutylammonium acetate, etc.);and the like.

The amount of the base is usually less than 1 mole per 1 mole of theBr.o slashed.nsted acid salt of the diazabicycloalkane of the formula(IV). To obtain the product of high purity, the amount of the base ispreferably 0.2 mole or less. More preferably, the amount of the base is0.1 mole or less in view of the yield and costs.

The form of fluorine (F₂) used in this reaction is the same as thatdescribed above. The preferable solvent and reaction temperatureemployed in this reaction are the same as those described above.

An HF addition salt may be formed when at least one of the aciddissociation constants pKa of the dibasic acid in the first and seconddissociation states is close to or larger than pKa of hydrogen fluoride(HF), that is, 3.17, in the case where the process of the presentinvention consists of or comprises the reaction with the fluorine whichwill be explained below. In this case, to prepare theN,N'-difluorodiazabicycloalkane salt of the formula (I) in which (X¹)⁻and (X²)⁻ together form a single conjugated base of the Br.oslashed.nsted acid, the HF addition salt is subjected to a treatment forremoving HF, for example, heating, vacuum drying, azeotropic boiling,and the like.

In the fourth embodiment of the present invention, a highly pureN,N'-difluorodiazoniabicycloalkane salt of the formula (I) is preparedin a high yield by reacting an acid or salt and aN,N'-difluorodiazoniabicycloalkane salt of the formula (I'): ##STR6##wherein (X¹ ')⁻ and (X2')⁻ represent independently each other aconjugated base of a Br.o slashed.nsted acid or together form a singleconjugated base of a Br.o slashed.nsted acid, and R¹, R², R³, R⁴, R⁵ andn are the same as defined above, which is obtained in the abovedescribed reaction, for inducing a counter anion exchange reaction.

The counter anion exchange reaction is preferably carried out using anacid for producing the highly pure product effectively.

In the above reaction, the acid may be a Br.o slashed.nsted acid orLewis acid.

The Br.o slashed.nsted may be the same as those described above.

The Lewis acid may be one having substantially the same acidity as thatof a Br.o slashed.nsted acid having an acid dissociation constant pKa ofabout 12.4 or less. The Lewis acid, which reacts with HF and forms aBr.o slashed.nsted acid having an acid dissociation constant of 4.6 orless, in particular, less than 3.17, is preferable. Examples of such theLewis acid are BF₃, BCl₃, BBr₃, AsF₃, AsF₅, PF₃, PF₅, PCl₅, SbF₃, SbCl₃,SbF₅, SbF₃ Cl₂, SbCl₅, AlF₃, AlCl₃, SiF₄, SO₃, (CF₃)₃ B, (C₆ H₂ F₃)₃ B,(C₆ F₅)₃ B, NbF₅, SeO₃, TaF₅, TeF₆, TiF₄, VF₅, ZrF₄, and the like.

The acid used in the above counter ion exchange reaction, that is, theBr.o slashed.nsted acid or Lewis acid may be used in the form of anaqueous solution or a complex with ethers (e.g. diethyl ether, dibutylether, dimethyl ether, t-butyl methyl ether, etc.); sulfides (e.g.dimethyl sulfide, diethyl sulfide, etc.); water; alcohols (e.g.methanol, ethanol, propanol, etc.); nitrites (e.g. acetonitrile,propionitrile, etc.); carboxylic acids (e.g. formic acid, acetic acid,etc.); and the like.

As the acid used in the above reaction, the Br.o slashed.nsted acid ispreferable for obtaining the product in the high yield.

The salt used in the above reaction may be the salt of the abovedescribed Br.o slashed.nsted acid. Preferable salts are metal salts,ammonium salts and phosphonium salts of the above exemplified Br.oslashed.nsted acids. Among them, the metal and ammonium salts arepreferable for obtaining the product of high purity at a low cost. Inparticular, the ammonium salts are preferable since the product isobtained in a high yield effectively.

Preferable examples of the ammonium moiety of the ammonium salt areammonium, monomethylammonium, dimethylammonium, trimethylammonium,tetramethylammonium, diethylammonium, triethylammonium,tetraethylammonium, tetrabutylammonium, benzyltrimethylammonium,benzyltriethylammonium, (hydroxyethyl)trimethylammonium,(hydroxyethyl)triethylammonium, pyridinium, N-methylpyridinium,quinolinium, and the like, and preferable examples of the metal saltsare alkali metal salts and alkaline earth metal salts.

The amount of the acid or salt is selected from a range between 0.75 and1.3 moles per 1 mole of the compound of the formula (I') when either oneof (X¹)⁻ and (X²)⁻ in the formula (I') is exchanged through the counteranion exchange reaction. However, 1.3 moles or more of the acid or saltmay be used. In such the case, preferably the amount of the acid or saltdoes not exceed 10 moles from the economical point of view.

The amount of the acid or salt is preferably at least 1.5 moles per 1mole of the compound of the formula (I') when both (X¹)⁻ and (X²)⁻ inthe formula (I') are exchanged. Preferably, the amount of the acid orsalt does not exceed 10 moles from the economical point of view.

When the N,N'-difluorodiazoniabicycloalkane salt of the formula (I) inwhich (X¹)⁻ and (X²)⁻ together form the single conjugated base of theBr.o slashed.nsted acid is prepared, the amount of the dibasic acid orits salt is preferably in a range between 0.75 and 1.3 moles, morepreferably between 0.9 and 1.2 moles per 1 mole of the compound of theformula (I').

The counter anion exchange reaction is carried out in a solventpreferably.

Examples of the solvent are C₂ -C₅ nitriles (e.g. acetonitrile,propionitrile, butyronitrile, isobutyronitrile, valeronitrile,isovaleronitrile, etc.); water; C₁ -C₅ alcohols or halogenated alcohols(e.g. methanol, ethanol, propanol, isopropanol, butanol, isobutanol,sec.-butanol, t-butanol, trifluoroethanol, trichloroethanol,tetrafluoropropanol, pentafluoropropanol, hexafluoroisopropanol,hexafluorobutanol, nonafluoro-t-butanol, octafluoropentanol,nonafluoropentanol, etc.); hydrogen fluoride; C₁ -C₄ alkanoic orhaloalkanoic acids (e.g. formic acid, acetic acid, propionic acid,butanoic acid, trifluoroacetic acid, tetrafluoropropionic acid,pentafluoropropionic acid, heptafluorobutanoic acid, etc.); and mixturesthereof.

The reaction temperature is usually selected from a range between about-100° C. and about +80° C. Preferably, the reaction temperature isbetween -80° C. and +50° C. for performing the reaction at the highyield.

According to the fifth embodiment of the present invention, aN,N'-difluorodiazoniabicycloalkane salt of the formula (I) can beproduced in a high yield by reacting the diazabicycloalkane of theformula (II) and the fluorine (F₂) in the presence of a Br.oslashed.nsted acid, followed by the reaction with an acid or salt.

The Br.o slashed.nsted acid used in this reaction may be the aboveexemplified ones. Among them, the oxoacids of sulfur are preferable inview of the yield and costs. In particular, sulfuric acid is preferablebecause of easy availability.

That is, the N,N'-difluorodiazoniabicycloalkane salt of the formula (I)can be produced with high purity at a high yield by reacting thediazabicycloalkane of the formula (II) and the fluorine (F₂) in thepresence of the Br.o slashed.nsted acid, preferably sulfuric acid, andthen reacting the intermediate product and the acid or salt.

The above process comprises the first step for reacting thediazabicycloalkane of the formula (II) and the fluorine in the presenceof the Br.o slashed.nsted acid, and the second step for treating theintermediate product obtained in the first step with the acid or salt.These steps will be explained below by referring to a case wheresulfuric acid which is particularly preferable as the Br.o slashed.nstedacid is used.

First step

Sulfuric acid used in this step is readily available as an inexpensiveindustrial raw material.

The form and amount of the fluorine (F₂) used in this step are the sameas described above.

The amount of sulfuric acid is preferably at least 0.45 mole, morepreferably between 0.45 and 5 moles, in particular between 0.5 and 3moles per 1 mole of the diazabicycloalkane. Furthermore, the amount ofsulfuric acid is desirably between 0.75 and 2.5 moles, more desirablybetween 0.9 and 2.2 moles in view of the high efficiency and yield.

A solvent is preferably used for performing the reaction in this step.Preferable examples of the solvent are C₂ -C₅ nitriles (e.g.acetonitrile, propionitrile, butyronitrile, isobutyronitrile,valeronitrile, isovaleronitrile, etc.); C₁ -C₈ halohydrocarbons (e.g.methylene chloride, chloroform, carbon tetrachloride,chlorotrifluoromethane, bromotrifluoromethane, dichloroethane,tetrachloroethane, tetrafluoroethane, chlorotrifluoroethane,perfluorobutane, perfluorohexane, perfluorooctane, etc.); water; C₁ -C₅alcohols or halogenated alcohols (e.g. methanol, ethanol, propanol,isopropanol, butanol, isobutanol, sec.-butanol, t-butanol,trifluoroethanol, trichloroethanol, hexafluoroisopropanol,pentafluoropropanol, tetrafluoropropanol, hexafluorobutanol,nonafluoro-t-butanol, octafluoropentanol, nonafluoropentanol, etc.);hydrogen fluoride; C₁ -C₄ alkanoic or haloalkanoic acids (e.g. formicacid, acetic acid, propionic acid, butanoic acid, trifluoroacetic acid,tetrafluoropropionic acid, pentafluoropropionic acid,heptafluorobutanoic acid, etc.); and mixtures thereof.

Among them, the C₂ -C₅ nitriles, C₁ -C₅ alcohols or halogenatedalcohols, C₁ -C₄ alkanoic or haloalkanoic acids or their mixtures arepreferable for performing the reaction effectively and obtaining theproduct in the high yield.

The reaction temperature is usually in the range between about -100° C.and about +80° C. Preferably, the reaction temperature is in the rangebetween -80° C. and +50° C. for performing the reaction in the highyield of the product.

Second step

In this step, the desired N,N'-difluorodiazoniabicycloalkane salt isobtained by reacting the acid or salt with the reaction liquidcontaining the N,N'-difluorodiazoniabicycloalkane sulfate and/ordi(hydrogensulfate) or hydrogensulfate/fluoride,hydrogen-sulfate/HF-addition fluoride, and the like.

The reaction in the second step comprises the counter anion exchangereaction for the N,N'-difluorodiazoniabicycloalkane salt formed in thefirst step. The acid is preferably used for the reaction in the secondstep to produce the product of high purity effectively.

In this reaction, a Br.o slashed.nsted acid or Lewis acid can be used asthe acid. The Br.o slashed.nsted acid or Lewis acid may be the same asdescribed above. As in the above described case, the Br.o slashed.nstedacid or Lewis acid may be used in the form of an aqueous solution or inthe form of a complex with ethers (e.g. diethyl ether, dimethyl ether,dibutyl ether, t-butyl methyl ether, etc.); sulfides (e.g. dimethylsulfide, diethyl sulfide, etc.); water; alcohols (e.g. methanol,ethanol, propanol, etc.); nitrites (e.g. acetonitrile, propionitrile,etc.); carboxylic acids (e.g. formic acid, acetic acid, etc.); and thelike.

The salt may be the salt of the above described Br.o slashed.nsted acid.Among the salts, the metal and ammonium salts are preferable forobtaining the highly pure product at a low cost. In particular, theammonium salts are preferable since the product is obtained in the highyield effectively.

Preferable examples of the ammonium moiety of the ammonium salt areammonium, monomethylammonium, dimethylammonium, trimethylammonium,tetramethylammonium, diethylammonium, triethylammonium,tetraethylammonium, tetrabutylammonium, benzyltrimethylammonium,benzyltriethylammonium, (hydroxyethyl)trimethylammonium,(hydroxyethyl)triethylammonium, pyridinium, N-methylpyridinium,quinolinium, and the like, and preferable examples of the metal saltsare alkali metal salts and alkaline earth metal salts.

The amount of the acid or salt is at least 0.8 mole per 1 mole of thediazabicycloalkane used in the first step, preferably at least 0.9 molein view of the yield, and more preferably 10 moles or less in view ofthe costs.

When N,N'-difluorodiazoniabicycloalkane salt of the formula (I) in which(X¹)⁻ and (X²)⁻ are the same (except a case where (X¹)⁻ and (X²)⁻ arethe conjugated base of the Br.o slashed.nsted acid used in the firststep), the amount of the acid or salt is preferably at least 1.5 moles,more preferably at least 1.7 moles, particularly at least 1.8 moles inview of the yield, and does not exceed 10 moles preferably from theeconomical point of view.

When the N,N'-difluorodiazoniabicycloalkane salt of the formula (I) inwhich (X¹)⁻ and (X²)⁻ together form the single conjugated base of theBr.o slashed.nsted acid is prepared, the amount of the dibasic acid orits salt is preferably in a range between 0.75 and 1.3 moles, morepreferably between 0.9 and 1.2 moles per 1 mole of thediazabicycloalkane. An HF addition salt may be formed, when the dibasicacid or its salt is used and at least one of the acid dissociationconstants pKa of the dibasic acid in the first and second dissociationstates is close to or larger than the pKa of hydrogen fluoride (HF),that is, 3.17. Such the HF addition salt is subjected to a treatment forremoving HF, for example, heating, vacuum drying, azeotropic boiling,and the like.

The reaction in the second step can be carried out by adding the acid orits salt or a compound containing the acid or salt to the reactionliquid obtained in the first step.

The reaction temperature is usually selected from a range between about-100° C. and about +80° C. Preferably, the reaction temperature isbetween -80° C. and +50° C. for performing the reaction in view of theyield and reaction efficiency.

For the post treatment of the reaction mixture, the desired product canbe isolated by filtration easily, when it is obtained in the form ofprecipitate.

In the sixth embodiment of the present invention, aN,N'-difluorodiazoniabicycloalkane salt of the formula (I) is alsoprepared in a high yield by reacting fluorine (F₂) and a monoBr.oslashed.nsted acid salt of a diazabicycloalkane of the formula (III'):##STR7## wherein R¹, R², R³, R⁴, R⁵, n and (X¹ ')⁻ are the same asdefined above, in the presence or absence of a Br.o slashed.nsted acid,and then reacting the intermediate product and an acid or salt.

This process comprises the step i) for reacting the fluorine and themonoBr.o slashed.nsted acid salt of the diazabicycloalkane of theformula (III') in the presence or absence of a Br.o slashed.nsted acid,and the step ii) for treating the intermediate product obtained in thestep i) with an acid or salt. These steps will be explained below indetail.

Step i)

The monoBr.o slashed.nsted acid salt of the diazabicycloalkane of theformula (III') used as the starting material in the step i) is readilyprepared by mixing the above diazabicycloalkane of the formula (II) withan equimolar amount of the Br.o slashed.nsted acid.

The Br.o slashed.nsted acid used in this reaction may be the aboveexemplified ones.

The Br.o slashed.nsted acid may not be used when (X¹ ')⁻ in the compoundof the formula (III') used as the starting material in this step is aconjugated base (HA⁻) of a dibasic acid in the first dissociation step(described below), while the Br.o slashed.nsted acid may be preferablyused in some cases depending on the acidity of the dibasic acid in thesecond dissociation state.

The Br.o slashed.nsted acid may not be used when (X¹)⁻ in the compoundof the formula (III') used as the starting material in this step is aconjugated base (A⁻) of a monobasic acid (described below), while theBr.o slashed.nsted acid may be preferably used for obtaining the productin the good yield.

When the use of the Br.o slashed.nsted acid is preferable, its amount ispreferably at least 0.1 mole per 1 mole of the monoBr.o slashed.nstedacid salt of the diazabicycloalkane of the formula (III') in view of theyield. Furthermore, when the acid dissociation constant pKa is 4.6 orless, the amount of the Br.o slashed.nsted acid is preferably between0.1 and 2 moles in view of the yield and costs. For effectivelyperforming the reaction at the high yield, the amount of the Br.oslashed.nsted acid is preferably between 0.2 and 1.5 moles, inparticular between 0.8 and 1.2 moles.

The form of the fluorine (F₂), reaction solvent and reaction temperaturein this step are the same as those employed in the above described firststep.

Step ii)

In this step, the acid or salt is reacted with the solution containingthe N,N'-difluorodiazoniabicycloalkane salt obtained in the step i), andthe desired N,N'-difluorodiazoniabicycloalkane salt of the formula (I)is obtained.

The reaction in the step ii) comprises a counter anion exchange reactionfor the N,N'-difluorodiazoniabicycloalkane salt. The acid is preferablyused for preparing the product of high purity effectively.

The acid used in this reaction may be the above exemplified Br.oslashed.nsted acids or Lewis acids. The acid may be used in the form ofa complex with various compounds, or in the form of an aqueous solutionas described above.

Examples of the salt are the same as those exemplified in the abovedescribed second step.

The amount of the acid or salt, reaction temperature, reaction mannerand post-treatment are the same as those in the above second step.

In the seventh embodiment of the present invention, aN,N'-difluorodiazoniabicycloalkane salt of the formula (I) is preparedin a high yield by reacting fluorine (F₂) and a Br.o slashed.nsted acidsalt of a diazabicycloalkane of the formula (IV'): ##STR8## wherein R¹,R², R³, R⁴, R⁵, n, (X¹ ')⁻ and (X² ')⁻ are the same as defined above, inthe presence or absence of a base, and then reacting the intermediateproduct and an acid or salt.

The Br.o slashed.nsted acid salt of the diazabicycloalkane of theformula (IV') is readily prepared by mixing the diazabicycloalkane ofthe formula (II) and at least one of the above exemplified Br.oslashed.nsted acid. Among them, the oxoacids of sulfur are preferable inview of the yield and costs. In particular, sulfuric acid is preferablebecause of easy availability.

The above process will be explained by referring to a case wheresulfuric acid, which is particularly preferable as the Br.oslashed.nsted acid, is used.

That is, the highly pure N,N'-difluorodiazoniabicycloalkane salt of theformula (I) is prepared in the high yield by reacting the fluorine (F₂)with a sulfate salt of a diazabicycloalkane of the formula (V): ##STR9##wherein R¹, R², R³, R⁴, R⁵ and n are the same as defined above, and/or adi(hydrogensulfate) salt of a diazabicycloalkane of the formula (VI):##STR10## wherein R¹, R², R³, R⁴, R⁵ and n are the same as definedabove, in the presence or absence of a base, and then reacting theintermediate product and an acid or salt.

This process comprises the step A for reacting the fluorine and thesulfate and/or di(hydrogensulfate) salt of the formulas (V), (V') and(VI) and the step B for treating the reaction product from the step Awith the acid or salt. Each step will be explained below.

Step A

The sulfate or di(hydrogensulfate) salt of the formulas (V), (V') or(VI") are readily prepared by reacting 1 or 2 equimolar amounts ofsulfuric acid and 1 equimolar amount of the diazabicycloalkane of theformula (II).

The form and amount of the fluorine (F₂) and the kind and amount of thebase are the same as those explained above. The reaction solvent andreaction temperature preferably used in this step are the same as thoseemployed in the above described first step.

Step B

In the step B, the reaction product obtained in the step A is treatedwith the acid or salt, and the procedures are the same as thoseexplained in the above second step. The acid is preferably used forpreparing the highly pure product effectively. The kind and amount ofthe acid or salt used in this step and the reaction temperature and thelike are the same as those employed in the above second step.

It is apparent that when the diazabicycloalkane of the formula (II) andthe Br.o slashed.nsted acid are reacted according to the presentinvention, the acid readily performs an acid-base reaction with thediazabicycloalkane as a base according to the following reaction schemesand forms various kinds of salts depending on the amount and acidity ofthe acid.

For example, when the acid is a monobasic Br.o slashed.nsted acid (HA):##STR11##

When the acid is a dibasic Br.o slashed.nsted acid (H₂ A): ##STR12##

Accordingly, the process using the presynthesized Br.o slashed.nstedacid salt of the diazabicycloalkane of the formula (III), (III'), (IV),(IV') (V), (V') or (VI) corresponds to the process using the specifiedamount of the acid for the diazabicycloalkane, since the monoBr.oslashed.nsted acid salt of the diazabicycloalkane of the formula (III)or (III'), the Br.o slashed.nsted acid salt of the diazabicycloalkane ofthe formula (IV) or (IV'), the sulfate salt of the diazabicycloalkane ofthe formula (V) or (V'), or the di(hydrogensulfate) salt of thediazabicycloalkane of the formula (VI) is one form of these salts.

Furthermore, the use of the Br.o slashed.nsted acid in an amount of lessthan 2 moles per 1 mole of the diazabicycloalkane of the formula (II)corresponds to the addition of the same diazabicycloalkane to thepresynthesized Br.o slashed.nsted acid salt of the diazabicycloalkane ofthe formula (IV) or (IV'). The use of the Br.o slashed.nsted in anamount exceeding 2 moles corresponds to the addition of the same Br.oslashed.nsted acid to the presynthesized Br.o slashed.nsted acid salt ofthe diazabicycloalkane of the formula (IV) or (IV').

For example, the addition of 1 mole of the same diazabicycloalkane tothe Br.o slashed.nsted acid salt of the diazabicycloalkane of theformula (IV) or (IV') corresponds to the use of 1 mole of the Br.oslashed.nsted acid for 1 mole of the diazabicycloalkane of the formula(II).

The use of 1 mole of the Br.o slashed.nsted acid for 1 mole of themonoBr.o slashed.nsted acid salt of the diazabicycloalkane of theformula (III) or (III') corresponds to the use of 2 moles of the Br.oslashed.nsted acid for 1 mole of the diazabicycloalkane of the formula(II).

The present invention also includes a fluorinating agent comprising thefollowing compounds:

N,N'-Difluoro-1,4-diazoniabicyclo 2.2.0!octane di(hydrogensulfate) ofthe formula: ##STR13##

N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane salt of the formula:##STR14## wherein n is a number of 0 to 10, and a method forfluorinating compounds using the fluorinating agent.

The compounds which are fluorinated are organic or inorganic compounds,preferably organic compounds. The organic compounds include any organiccompounds such as saturated aliphatic organic compounds, unsaturatedaliphatic organic compounds, aromatic organic compounds, condensedaromatic organic compounds, saturated heteroaliphatic organic compounds,unsaturated heteroaliphatic organic compounds, heteroaromatic organiccompounds, organometallic compounds, organic polymers, and the like.Among them, nucleophilic organic compounds are preferable.

Among the N,N'-difluorodiazoniabicycloalkane salts of the formula (I),N,N'-difluoro-1,4-diazoniabicyclo 2.2.0!octane di(hydrogensulfate) andN,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane hydrogensulfate fluorideor its poly(hydrogen fluoride) adduct are particularly useful as usefulintermediates or fluorinating agents which are cheap and have highfluorination efficiencies.

EXAMPLES

The present invention will be illustrated by the following examples,which do not limit the scope of the present invention in any way.

Example 1 ##STR15##

1,1,1,3,3,3-Hexafluoro-2-propanol (40 ml) was added to 1,4-diazabicyclo2.2.2!octane (10.0 mmol, 1.12 g) in a 200 ml egg plant-type flask. Afterreplacing the internal atmosphere in the flask with argon, the mixturewas stirred to form a homogeneous solution. Then, conc. sulfuric acid(19.9 mmol, 1.95 g, 1.1 ml) was added to the solution.

The flask was dipped in a bath kept at -5° C., and diluted fluorine gas(F₂ /N₂ =10/90 (v/v)) was blown in the solution at a flow rate of 40ml/min. while stirring well. The reaction was terminated after blowing11,300 ml of the diluted fluorine gas (50.4 mmol of fluorine). After theresidual fluorine gas was purged by flowing nitrogen gas, the reactionmixture was allowed to warm up to room temperature.

The crystal precipitated by the addition of diethyl ether (50 ml) wasfiltrated, and colorless solid N,N'-difluoro-1,4-diazoniabicyclo2.2.2!octane di(hydrogensulfate) having the purity of 100% (mole %) (3.0g, 8.72 mmol) was obtained. Yield: 82%.

The properties were shown in Table 1.

Example 2 ##STR16##

1,1,1,3,3,3-Hexafluoro-2-propanol (40 ml) was added to 1,4-diazabicyclo2.2.2!octane (20.0 mmol, 2.24 g) in a 100 ml egg plant-type flask. Afterreplacing the internal atmosphere in the flask with argon, the mixturewas stirred to form a homogeneous solution. Then,trifluoromethanesulfonic acid (39.0 mmol, 5.85 g) was added to thesolution.

The flask was dipped in a bath kept at 0° C., and diluted fluorine gas(F₂ /N₂ =10/90 (v/v)) was blown in the solution at a flow rate of 50ml/min. while stirring well. The reaction was terminated after blowing26,880 ml of the diluted fluorine gas (120 mmol of fluorine). After theresidual fluorine gas was purged by flowing nitrogen gas, the reactionmixture was allowed to warm up to room temperature.

The solvent was evaporated off from the reaction liquid under reducedpressure, the obtained crystalline solid was recrystallized fromacetonitrile, and N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(trifluoromethanesulfonate) having the purity of 100% (5.73 g) wasobtained. Yield: 64%.

The properties were shown in Table 1.

Example 3 ##STR17##

Acetonitrile (12 ml) was added to 1,4-diazabicyclo- 2.2.2!octane (3.0mmol, 337 mg) in a 100 ml egg plant-type flask. After replacing theinternal atmosphere in the flask with argon, trifluoromethanesulfonicacid (5.85 mmol, 878 mg) was added to the mixture.

The flask was dipped in a bath kept at -30° C., and diluted fluorine gas(F₂ /N₂ =10/90 (v/v)) was blown in the solution at a flow rate of 30ml/min. while stirring well. The reaction was terminated after blowing4023 ml of the diluted fluorine gas (18 mmol of fluorine). After theresidual fluorine gas was purged by flowing nitrogen gas, the reactionmixture was allowed to warm up to room temperature.

The solvent was evaporated off from the reaction liquid under reducedpressure. The residual solid was thoroughly washed with diethyl ether,and N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(trifluoromethanesulfonate) (1.13 g, yield: 84%) was obtained.

This product was analyzed by ¹ H- and ¹⁹ F-NMR. The purity ofN,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(trifluoromethanesulfonate) was 95%, and 5% ofN,N-dihydro-1,4-diazoniabicyclo 2.2.2!octanebis(trifluoromethanesulfonate) was contained as the impurity.

After adding trifluoromethanesulfonic acid (45 mg, 0.3 mmol) was addedto the above product (1.13 g), the product was recrystallized fromacetonitrile, and N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(trifluoromethanesulfonate) having the purity of 100% (0.834 g) wasobtained. Yield: 62%.

The properties were shown in Table 1.

Example 4 ##STR18##

1,1,1,3,3,3-hexafluoro-2-propanol (12 ml) and sulfuric acid (3.0 mmol,0.249 g) were added to 1,4-diazabicyclo 2.2.2!octane (3.0 mmol, 337 mg)in a 50 ml egg plant-type flask.

The flask was dipped in a bath kept at -5° C., and diluted fluorine gas(F₂ /N₂ =10/90 (v/v)) was blown in the reaction liquid at a flow rate of30 ml/min. while stirring well. The reaction was terminated afterblowing 4032 ml of the diluted fluorine gas (18 mmol of fluorine). Afterthe residual fluorine gas was purged by flowing nitrogen gas, thereaction mixture was allowed to warm up to room temperature.

The reaction liquid was concentrated under reduced pressure. Afteradding methylene chloride, the formed crystal was filtrated. Theobtained crystal was thoroughly washed with methylene chloride, andcolorless solid N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanehydrogensulfate di(hydrogen fluoride) fluoride having the purity of 100%(0.588 g) was obtained. Yield: 61%.

The properties were shown in Table 1.

Example 5 ##STR19##

N,N'-Difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(trifluoromethanesulfonate) (8.0 mmol, 3.61 g) was charged in a 100ml round flask. After replacing the internal atmosphere in the flaskwith argon, 1,1,1,3,3,3-hexafluoro-2-propanol (36 ml) was added whilestirring to form a homogeneous solution. Then, a tetrafluoroboricacid-diethyl ether complex (20 mmol, 3.24 g) was dropwise added to thesolution at room temperature, followed by stirring for one hour. Theprecipitated crystal was filtrated.

The collected crystal was thoroughly washed with methylene chloride, andcolorless solid N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(tetrafluoroborate) having the purity of 100% (7.24 mmol, 2.34 g) wasobtained. Yield: 90%.

The properties were shown in Table 2.

Example 6 ##STR20##

N,N'-Difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(trifluoromethanesulfonate) (1.19 mmol, 0.535 g) was charged in a 30ml round flask. After replacing the internal atmosphere in the flaskwith argon, 1,1,1,3,3,3-hexafluoro-2-propanol (5 ml) was added whilestirring to form a homogeneous solution. Then, a 60% aqueous solution ofhexafluorophosphoric acid (2.6 mmol, 0.385 g) was dropwise added to thesolution at room temperature, followed by stirring for 15 minutes.

The precipitated crystal was thoroughly washed with diethyl ether, andcolorless solid N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(hexafluorophosphate) having the purity of 100% (0.348 g) wasobtained.

Diethyl ether was added to the filtrate. The precipitated crystal wasfiltrated and thoroughly washed with diethyl ether, andN,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane bis(hexafluorophosphate)having the purity of 100% (0.093 g) was obtained. Total yielded amount:0.441 g (total yield: 85%).

The properties were shown in Table 2.

Example 7 ##STR21##

N,N'-Difluoro-1,4-diazoniabicyclo 2.2.2!octane hydrogensulfatedihydrogen fluoride fluoride (0.246 g, 0.81 mmol) was charged in a 10 mlegg plant-type flask, and 1,1,1,3,3,3-hexafluoro-2-propanol (4 ml) wasadded. Then, a tetrafluoroboric acid-diethyl ether complex (0.356 g, 2.2mmol) was dropwise added at room temperature, followed by stirring forone hour at room temperature. The precipitated crystal was filtrated.

The obtained crystal was thoroughly washed with diethyl ether, andcolorless solid N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(tetrafluoroborate) having the purity of 100% (0.262 9) was obtained.Yield: 100%.

The properties were shown in Table 2.

Example 8 ##STR22##

A tetrafluoroboric acid-diethyl ether complex (0.679 g, 4.2 mmol) wasdropwise added to a suspension of N,N'-difluoro-1,4-diazoniabicyclo2.2.2!octane di(hydrogensulfate) (0.669 g, 2.0 mmol) in acetonitrile (4ml) which was well stirred at room temperature, followed by stirring forfurther 15 minutes at room temperature. The precipitated crystal wasfiltrated and washed with ether, followed by drying under reducedpressure, and N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(tetrafluoroborate) having the purity of 100% (0.530 g) was obtained.Yield: 82%.

The properties were shown in Table 2.

Example 9 ##STR23##

A tetrafluoroboric acid-diethyl ether complex (0.706 g, 4.37 mmol) wasdropwise added to a suspension of N,N'-difluoro-1,4-diazoniabicyclo2.2.2!octane bis(hexafluoroantimonate) (1.29 g, 2.08 mmol) inacetonitrile (8 ml) which was well stirred at room temperature, followedby stirring for further 15 minutes at room temperature. The precipitatedcrystal was filtrated and washed with ether, followed by drying underreduced pressure, and N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(tetrafluoroborate) having the purity of 100% (0.650 g) was obtained.Yield: 97%.

The properties were shown in Table 2.

Example 10 ##STR24##

1,1,1,3,3,3-Hexafluoro-2-propanol (60 ml) was added to 1,4-diazabicyclo2.2.2!octane (15.0 mmol, 1.68 g) in a 200 ml egg plant-type flask. Afterreplacing the internal atmosphere in the flask with argon, the mixturewas stirred to form a homogeneous solution. Then, conc. sulfuric acid(15.0 mmol, 1.47 9) was added to the solution.

The flask was dipped in a bath kept at -5° C., and diluted fluorine gas(F₂ /N₂ =10/90 (v/v)) was blown in the solution at a flow rate of 40ml/min. The diluted fluorine gas of 20,160 ml (90 mmol of fluorine) wasblown. Then, the residual fluorine gas was purged by flowing nitrogengas.

After allowing the reaction mixture to warm up to room temperature, atetrafluoroboric acid-diethyl ether complex (33 mmol, 5.34 g) wasdropwise added, followed by stirring for 30 minutes. The precipitatedcrystal was filtrated and washed with diethyl ether, and colorless solidN,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane bis(tetrafluoroborate)having the purity of 100% (11.6 mmol, 3.76 g) was obtained. Yield: 77%.

The properties were shown in Table 2.

Example 11 ##STR25##

2,2,2-Trifluoroethanol (12 ml) was added to 1,4-diazabicyclo2.2.2!octane (3.0 mmol, 337 mg) in a 50 ml egg plant-type flask. Afterreplacing the internal atmosphere in the flask with argon, conc.sulfuric acid (3.0 mmol, 249 mg) was added to the solution whilestirring.

The flask was dipped in a bath kept at -5° C., and diluted fluorine gas(F₂ /N₂ =10/90 (v/v)) was blown in the solution at a flow rate of 30ml/min. The diluted fluorine gas of 5136 ml (23 mmol of fluorine) wasblown. Then, the residual fluorine gas was purged by flowing nitrogengas.

After allowing the reaction mixture to warm up to room temperature, a42% aqueous solution of tetrafluoroboric acid (1.38 g, 6.6 mmol oftetrafluoroboric acid) was dropwise added while stirring, and additional2,2,2-trifluoroethanol (30 ml) was added, followed by stirring for 13hours at room temperature. The precipitated crystal was filtrated andthoroughly washed with diethyl ether, and colorless solidN,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane bis(tetrafluoroborate)having the purity of 100% (608 mg, 1.88 mmol) was obtained. Yield: 63%.

The properties were shown in Table 2.

Example 12 ##STR26##

1,1,1,3,3,3-Hexafluoro-2-propanol (12 ml) was added to 1,4-diazabicyclo2.2.2!octane (3.0 mmol, 337 mg) in a 50 ml egg plant-type flask. Afterreplacing the internal atmosphere in the flask with argon, conc.sulfuric acid (3.0 mmol, 249 mg) was added to the solution whilestirring.

The flask was dipped in a bath kept at -5° C., and diluted fluorine gas(F₂ /N₂ =10/90 (v/v)) was blown in the solution at a flow rate of 30ml/min. The diluted fluorine gas of 4032 ml (18 mmol of fluorine) wasblown. Then, the residual fluorine gas was purged by flowing nitrogengas.

After allowing the reaction mixture to warm up to room temperature, asolution of antimony pentafluoride (6.6 mmol, 1.43 g) in1,1,1,3,3,3-hexafluoro-2-propanol (10 ml) was dropwise added, followedby stirring for 45 minutes. The precipitated crystal was filtrated andthoroughly washed with methylene chloride and colorless solidN,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane bis(hexafluoroantimonate)having the purity of 100% (2.60 mmol, 1.62 g) was obtained. Yield: 87%.

The properties are shown in Table 2.

Example 13 ##STR27##

2,2,2-Trifluoroethanol (12 ml) was added to 1,4-diazabicyclo2.2.2!octane (3.0 mmol, 0.337 g) in a 100 ml egg plant-type flask. Afterreplacing the internal atmosphere in the flask with argon, the mixturewas stirred to form a homogeneous solution. Then, conc. sulfuric acid(3.0 mmol, 0.249 g) was added to the solution.

The flask was dipped in a bath kept at -30° C., and diluted fluorine gas(F₂ /N₂ =10/90 (v/v)) was blown in the solution at a flow rate of 30ml/min. while stirring well. The fluorine gas of 4023 ml (18 mmol offluorine) was blown. Then, the residual fluorine gas was purged byflowing nitrogen gas.

After allowing the reaction mixture to warm up to room temperature, atetrafluoroboric acid-diethyl ether complex (6.6 mmol, 1.07 g) wasdropwise added, followed by stirring for one hour. The precipitatedcrystal was filtrated and thoroughly washed with diethyl ether, andcolorless solid N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(tetrafluoroborate) having the purity of 100% (0.804 g) was obtained.Yield: 83%.

The properties were shown in Table 2.

Example 14 ##STR28##

Acetonitrile (12 ml) was added to 1,4-diazabicyclo 2.2.2!octane (3.0mmol, 0.337 g) in a 100 ml egg plant-type flask. After replacing theinternal atmosphere in the flask with argon, the mixture was stirred toform a homogeneous solution. Then, conc. sulfuric acid (3.0 mmol, 0.294g) was added to the solution.

The flask was dipped in a bath kept at -30° C., and diluted fluorine gas(F₂ /N₂ =10/90 (v/v)) was blown in the solution at a flow rate of 30ml/min. while stirring well. The fluorine gas of 4635 ml (20.7 mmol offluorine) was blown. Then, the residual fluorine gas was purged byflowing nitrogen gas.

After allowing the reaction mixture to warm up to room temperature, atetrafluoroboric acid-diethyl ether complex (6.6 mmol, 1.07 g) wasdropwise added, followed by stirring for one hour. The crystal, whichwas precipitated by the addition of diethyl ether, was filtrated andthoroughly washed with diethyl ether, and colorless solidN,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane bis(tetrafluoroborate)having the purity of 100% (0.621 g) was obtained. Yield: 64%.

The properties were shown in Table 2.

Example 15 ##STR29##

Acetonitrile (12 ml) was added to 1,4-diazabicyclo 2.2.2!octane (0.337mg, 3.0 mmol) in a 100 ml egg plant-type flask. After replacing theinternal atmosphere in the flask with argon, conc. sulfuric acid (0.294g, 3.0 mmol) was dropwise added to the solution at room temperature.

The flask was dipped in a bath kept at -30° C., and diluted fluorine gas(F₂ /N₂ =10/90 (v/v)) was blown in the solution at a flow rate of 30ml/min. while stirring well. The reaction was terminated after 4032 mlof the diluted fluorine gas (18.0 mmol of fluorine) was blown. Then, theresidual fluorine gas was purged by flowing nitrogen gas.

After that, a boron trifluoride-diethyl ether complex (0.937 g, 6.6mmol) was dropwise added to the reaction solution. Then, the reactionmixture was allowed to warm up to room temperature, followed by stirringfor additional 10 minutes. The precipitated crystal was filtrated andthoroughly washed with methylene chloride and colorless solidN,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane bis(tetrafluoroborate)having the purity of 100% (0.695 g) was obtained. Yield: 72%.

The properties were shown in Table 2.

                                      TABLE 1    __________________________________________________________________________    Properties of N,N'-difluorodiazoniabicycloalkane salts            .sup.1 H-NMR                       .sup.19 F-NMR    Decom-  (ppm,      (ppm,     IR    Elemental analysis    Ex.       position            TMS, int.  CFCl.sub.3, int.                                 (cm.sup.-1,                                       Found (%)     Calculated (%)    No.       temp.            standard)  standard) nujol)                                       C  H  N  F  S C  H  N  F  S    __________________________________________________________________________    1   80° C.            4.64 (br, s)                       42.6 (br, s)                                 3048, 1266,                                       20.75                                          4.50                                             7.94                                                -- --                                                     20.93                                                        4.10                                                           8.14                                                              -- --            in D.sub.2 SO.sub.4                       in D.sub.2 SO.sub.4                                 1168, 1019                                 854    2, 3,       about            5.07 (dd, J = 3.5, 3.5 Hz)                       39.2 (2F, br, s, 2xNF)                                 3039, 1262,                                       21.42                                          2.77                                             6.04                                                -- --                                                     21.43                                                        2.70                                                           6.25                                                              -- --    26 170° C.*            in CD.sub.3 CN                       -78.1 (6F, s, 2xCF.sub.3)                                 1169, 1037,                       in CD.sub.3 CN                                 867    4  100° C.            4.64 (br, s)                       39.8 (br, s)                                 3051, 1270,                                       21.49                                          4.64                                             8.12                                                27.9                                                   8.5                                                     21.30                                                        4.47                                                           8.28                                                              28.1                                                                 9.5            in D.sub.2 SO.sub.4                       -127 (v.br. peak)                                 1228, 1045,                       in DCOOD  874    __________________________________________________________________________     Note: *Starting temperature of the decomposition measured by a     differential scanning calorimeter (at a heating rate of 10°     C./min.)

                                      TABLE 2    __________________________________________________________________________    Properties of N,N'-difluorodiazoniabicycloalkane salts                        .sup.19 F-NMR    Decom-   .sup.1 H-NMR                        (ppm,     IR    Elemental analysis    Ex. position             (ppm, TMS, int.                        CFCl.sub.3, int.                                  (cm.sup.-1,                                        Found (%)                                                 Calculated (%)    No. temp.             standard)  standard) nujol)                                        C  H  N  C  H  N    __________________________________________________________________________    5, 7-11,        about             5.02 (dd, J=3.5, 3.5 Hz)                        39.2 (2F, br.s, 2xNF)                                  3072, 1062,                                        22.35                                           3.61                                              8.39                                                 22.26                                                    3.74                                                       8.65    13-15        170° C.*             in CD.sub.3 CN                        -150.2    851    25                  (8F, s, 2xBF.sub.4)                        in CD.sub.3 CN    6, 23        about             4.95 (dd, J=3.5, 3.5 Hz)                        38.9 (2F, br.s, 2xNF)                                  3073, 1103,                                        16.58                                           2.76                                              6.41                                                 16.38                                                    2.75                                                       6.37        155° C.*             in CD.sub.3 CN                        -69.5     861, 831,                        (12F, d, J=352 Hz,                                  559                        2xPF.sub.6)                        in CD.sub.3 CN    12  about             4.96 (dd,  38.9 (2F, br.s, 2xNF)                                  3067, 1102,                                        11.76                                           1.86                                              4.43                                                 11.59                                                    1.95                                                       4.51        200° C.             J=3.5, 3.5 Hz)                        -96.5 to -150.0                                  853, 662,             in CD.sub.3 CN                        (12F, br.m, 2xSbF.sub.6)                                  635                        in CD.sub.3 CN    __________________________________________________________________________     Note: *Starting temperature of the decomposition measured by a     differential scanning calorimeter (at a heating rate of 10°     C./min.)

Examples 16-22 ##STR30##

A reaction and post-treatment were carried out in the same manner as inExample 15 except that raw materials shown in Table 3 in amounts ofTable 3 were reacted with dilute fluorine gas at -20° C., and theobtained crystal was washed with methylene chloride and diethyl ether.The results are also shown in Table 3.

As understood from Table 3, completely or substantially pureN,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane bis(tetrafluoroborate)was obtained in the high yield.

When the purity was less than 100% in Table 3, the impurity wasN,N'-dihydro-1,4-diazoniabicyclo 2.2.2!octane bis(tetrafluoroborate).

                                      TABLE 3    __________________________________________________________________________                                 ##STR31##    Ex. No.        ##STR32##             Amount of H.sub.2 SO.sub.4                  Amount of BF.sub.3.OEt.sub.2                        ##STR33## Yield Purity    __________________________________________________________________________    16 3 mmol             3.06 mmol                  6.48 mmol                       1/1.02     62%   100%    17 3 mmol             3.12 mmol                  6.51 mmol                       1/1.04     65%   100%    18 3 mmol             3.39 mmol                  6.33 mmol                       1/1.13     77%    98.2%    19 3 mmol             3.93 mmol                  6.36 mmol                       1/1.31     83%   >99.8%    20 3 mmol              4.5 mmol                  6.36 mmol                       1/1.5      88%   100%    21 3 mmol             5.13 mmol                  6.36 mmol                       1/1.71     87%    99.6%    22 3 mmol             6.00 mmol                  6.36 mmol                       1/2.00     81%    97.2%    __________________________________________________________________________

Example 23 ##STR34##

1,4-Diazabicyclo 2.2.2!octane (45.1 mmol, 5.06 g) was charged in a 100ml round flask made of POLYFLON (trademark, polytetrafluoroethylenemanufactured by DAIKIN INDUSTRIES, LTD.). After replacing the internalatmosphere in the flask with argon, acetonitrile (50 ml) was added.

After cooling the solution to 0° C., a 60% aqueous solution ofhexafluorophosphoric acid (HPF₆) (94.7 mmol) was added to the solutionwhile stirring, followed by evaporating off the solvent at roomtemperature under reduced pressure. The obtained solid was thoroughlywashed with diethyl ether and then dried, andN,N'-dihydro-1,4-diazoniabicyclo 2.2.2!octane bis(hexafluorophosphate)was obtained quantitatively.

N,N'-Dihydro-1,4-diazoniabicyclo 2.2.2!octane bis(hexafluorophosphate)(3.0 mmol, 1.21 g) was charged in a separate 100 ml round flask made ofPOLYFLON. After replacing the internal atmosphere in the flask withargon, acetonitrile (12 ml) was added and stirred to form a solution.Then, the flask was dipped in a bath kept at -30° C., and dilutedfluorine gas (F₂ /N₂ =10/90 (v/v)) was blown in the solution at a flowrate of 30 ml/min. while stirring well. The diluted fluorine gas of 4032ml (18 mmol of fluorine) was blown. Then, the residual fluorine gas waspurged by flowing nitrogen gas.

After allowing the reaction mixture to warm up to room temperature,insoluble materials were filtrated off. The solvent was evaporated offfrom the filtrate, followed by drying under reduced pressure, andcolorless crystalline N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(hexafluorophosphate) having the purity of 100% (1.07 g) wasobtained. Yield: 81%.

The properties were shown in Table 2.

Example 24

Anisole was fluorinated with N,N'-difluoro-1,4-diazoniabicyclo2.2.2!octane di(hydrogensulfate) according to the present invention as afluorinating agent under the reaction condition shown in Table 4. Theresults are also shown in Table 4.

As seen from Example 24, the fluorination proceeds smoothly under thecondition of room temperature and the reaction time of 15 minutes informic acid, and fluoroanisoles are formed in the good yields, whenN,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane salt comprising thehydrogensulfate ion (HSO₄ ⁻), which has a proton for activating thefluorination reaction as a counter anion, is used. Accordingly, theN,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane di(hydrogensulfate), andhydrogensulfate fluoride or its poly(hydrogen fluoride) which have theactivation ability by themselves are expected to achieve the highfluorination efficiency in the fluorination carried out in a neutralorganic solvent, and therefore they seem to be promising fluorinatingagents having a wide variety of applications.

                                      TABLE 4    __________________________________________________________________________     ##STR35##     ##STR36##                                         Conversion                                               Yieids of products (%)          Fluorinating         Reaction                                    Reaction                                         of anisole                                               o-Fluoro-                                                    p-Fluoro-                                                         2,4-Difluoro-          agent      Anisole                          Solvent                               time temp.                                         (%)   anisole                                                    anisole                                                         anisole                                                               Total    __________________________________________________________________________    Example 24           ##STR37## 1 mmol                          HCOOH                               15 min.                                    Room 92    33   29   4     66                          2 ml      temp.    __________________________________________________________________________

Example 25 ##STR38##

A boron trifluoride-diethyl ether complex (1.55 g, 10.9 mmol) was addedto a solution of N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanehydrogensulfate di(hydrogen fluoride) fluoride (1.76 g, 5.2 mmol) in1,1,1,3,3,3-hexafluoro-2-propanol (5 ml) in a nitrogen atmosphere atroom temperature. After stirring the solution at room temperature for 15minutes, the solid was filtrated and washed with1,1,1,3,3,3-hexafluoro-2-propanol, dichloromethane and then diethylether (each one time), followed by drying under reduced pressure, andcrystalline N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(tetrafluoroborate) having the purity of 100% (1.10 g) was obtained.Yield: 66%.

The properties are shown in Table 2.

Example 26 ##STR39##

1,1,1,3,3,3-hexafluoro-2-propanol (12 ml) was added to 1,4-diabicyclo2.2.2!octane monotrifluoromethanesulfonate salt (3.0 mmol, 0.787 g) in a100 ml egg plant-type flask. After replacing the internal atmosphere inthe flask with argon, the mixture was stirred to form a homogeneoussolution, and trifluoromethane-sulfonic acid (2.85 mmol, 0.428 g) wasadded to the solution.

The flask was dipped in a bath kept at 0° C., and diluted fluorine gas(F₂ /N₂ =10/90 (v/v)) was blown in the solution at a flow rate of 30ml/min. while stirring well. The reaction was terminated after 4032 mlof the diluted fluorine gas (18.0 mmol of fluorine) was blown. Then, theresidual fluorine gas was purged by flowing nitrogen gas.

After allowing the reaction mixture to warm up to room temperature, thesolvent was evaporated off from the reaction liquid under reducedpressure, and the desired product having the purity of 98% (1.45 g) wasobtained (quantitative yield). This crystalline solid was recrystallizedfrom acetonitrile, and N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octanebis(trifluoromethane-sulfonate) having the purity of 100% (0.816 g) wasobtained. Yield: 61%.

The properties were shown in Table 1.

What is claimed is:
 1. A process for preparing aN,N'-difluorodiazoniabicycloalkane salt of the formula (I): ##STR40##wherein R¹, R², R³, R⁴ and R⁵ represent independently of each other ahydrogen atom, a C₁ -C₆ alkyl group, an aryl group, a C₁ -C₆ alkylgroup-substituted aryl group or an aryl group-substituted C₁ -C₆ alkylgroup, (X¹)⁻ and (X²)⁻ represent independently of each other aconjugated base of a Br.o slashed.nsted acid or together form a singleconjugated base of a Br.o slashed.nsted acid, and n is 0, 1 or 2,comprising the step of reacting fluorine and a diazabicycloalkane of theformula (II): ##STR41## wherein R¹, R², R³, R⁴, R⁵ and n are the same asdefined above in the presence of a Br.o slashed.nsted acid.
 2. Theprocess for preparing a N,N'-difluorodiazoniabicycloalkane salt of theformula (I): ##STR42## wherein R¹, R², R³, R⁴, R⁵, n, (X¹)⁻ and (X²)⁻are the same as defined in claim 1, comprising the step of reactingfluorine and a monoBr.o slashed.nsted acid salt of a diazabicycloalkaneof the formula (III): ##STR43## wherein R¹, R², R³, R⁴, R⁵, n and (X¹)⁻are the same as defined above, in the presence or absence of a Br.oslashed.nsted acid.
 3. The process for preparing aN,N'-difluorodiazoniabicycloalkane salt of the formula (I): ##STR44##wherein R¹, R², R³, R⁴, R⁵, n, (X¹)⁻ and (X²)⁻ are the same as definedin claim 1, comprising the step of reacting fluorine and a Br.oslashed.nsted acid salt of a diazabicycloalkane of the formula (IV):##STR45## wherein R¹, R², R³, R⁴, R⁵, n, (X¹)⁻ and (X²)⁻ are the same asdefined in claim 1, in the presence or absence of a base.
 4. The processfor preparing a N,N'-difluorodiazoniabicycloalkane salt of the formula(I): ##STR46## wherein R¹, R², R³, R⁴, R⁵, n, (X¹)⁻ and (X²)⁻ are thesame as defined in claim 1, comprising the step of reacting an acid orsalt and a N,N'-difluorodiazoniabicycloalkane salt of the formula (I'):##STR47## wherein (X¹ ')⁻ and (X² ')⁻ represent independently of eachother a conjugated base of a Bronsted acid or together form a singleconjugated base of a Bronsted acid wherein at least one of (X¹)⁻ and(X²)⁻ is different from at least one of (X¹ ')⁻ and (X² ')⁻, wherein acombination of (X¹)⁻ and (X²)⁻ is different from a combination of (X¹')⁻ and (X² ')⁻, and R¹, R², R³, R⁴, R⁵ and n are the same as defined inclaim
 1. 5. N,N'-difluoro-1,4-diazoniabicyclo 2.2.2!octane salt of theformula: ##STR48## wherein n is a number of 0 to
 10. 6. The process forpreparing a N,N'-difluorodiazoniabicycloalkane salt of the formula (I):##STR49## wherein R¹, R², R³, R⁴, R⁵, n, (X¹)⁻ and (X²)⁻ are the same asdefined in claim 1, comprising the steps of reacting fluorine and adiazabicycloalkane of the formula (II): ##STR50## wherein R¹, R², R³,R⁴, R⁵ and n are the same as defined in claim 1, in the presence of aBr.o slashed.nsted acid, and then reacting the intermediate product withan acid or salt.
 7. A process for preparing aN,N'-difluorodiazoniabicycloalkane salt of the formula (I): ##STR51##wherein R¹, R², R³, R⁴, R⁵, n, (X¹)⁻ and (X²)⁻ are the same as definedin claim 1, comprising the steps of reacting fluorine and adiazabicycloalkane of the formula (II): ##STR52## wherein R¹, R², R³,R⁴, R⁵ and n are the same as defined in claim 1, in the presence ofsulfuric acid, and then reacting the intermediate product and an acid orsalt.
 8. The process for preparing a N,N'-difluorodiazoniabicycloalkanesalt of the formula (I): ##STR53## wherein R¹, R², R³, R⁴, R⁵, n, (X¹)⁻and (X²)⁻ are the same as defined in claim 1, comprising the steps ofreacting fluorine and a monoBr.o slashed.nsted acid salt of adiazabicycloalkane of the formula (III'): ##STR54## wherein R¹, R², R³,R⁴, R⁵, n and (X¹ ')⁻ are the same as defined in claims 1 and 4, in thepresence or absence of a Br.o slashed.nsted acid, and then reacting theintermediate product with an acid or salt.
 9. The process for preparinga N,N'-difluorodiazoniabicycloalkane salt of the formula (I): ##STR55##wherein R¹, R², R³, R⁴, R⁵, n, (X¹)⁻ and (X²)⁻ are the same as definedin claim 1, comprising the steps of reacting fluorine and a Br.oslashed.nsted acid salt of a diazabicycloalkane of the formula (IV'):##STR56## wherein R¹, R², R³, R⁴, R⁵, n, (X¹ ')⁻ and (X² ')⁻ are thesame as defined in claims 1 or 4, in the presence or absence of a base,and then reacting the intermediate product with an acid or salt.
 10. Theprocess for preparing a N,N'-difluorodiazoniabicycloalkane salt of theformula (I): ##STR57## wherein R¹, R², R³, R⁴, R⁵, n, (X¹)⁻ and (X²)⁻are the same as defined in claim 1, comprising the steps of reactingfluorine and a sulfate salt of a diazabicycloalkane of the formula (V):##STR58## and/or the formula (V'): ##STR59## wherein R¹, R², R³, R⁴, R⁵and n are the same as defined in claim 1, and/or a di(hydrogensulfate)salt of a diazabicycloalkane of the formula (VI): ##STR60## wherein R¹,R², R³, R⁴, R⁵ and n are the same as defined in claim 1, in the presenceor absence of a base, and then reacting the intermediate product with anacid or salt.
 11. The process according to claim 3, 9 or 10, wherein abase is an amine or an ammonium compound that is a base when thereaction is carried out in the presence of a base.
 12. The processaccording to claims 3, 9, and 10, wherein the amount of a base is lessthan 1 mole per one mole of a Br.o slashed.nsted acid salt of adiazobicycloalkane of the formula (IV) or (IV'), a sulfate salt of adiazobicycloalkane of the formula (V) or (V'), or a di(hydrogensulfate)salt of a diazobicycloalkane of the formula (VI).
 13. The processaccording to claim 1, wherein a solvent is used.
 14. The processaccording to claim 13, wherein said solvent is at least one solventselected from the group consisting of C₂ -C₅ nitriles, C₁ -C₅halohydrocarbons, C₁ -C₅ alcohols or halogenated alcohols and C₁ -C₄alkanoic or haloalkanoic acids.
 15. The process according to claim 14,wherein said nitrile is acetonitrile or propionitrile; saidhalohydrocarbon is methylene chloride, chloroform, carbon tetrachloride,trichlorofluoromethane, bromotrofluoromethane, dichloroethne ortrichlorotrifluoroethane; said alcohols or halogenated alcohol ismethanol, ethanol, propanol, isopropanol, butanol, isobutanol,sec.-butanol, t-butanol, trifluoroethanol, trichloroethanol,pentafluoropropanol, tetrafluoropropanol, hexafluoroisopropanol,heptafluorobutanol, nonafluoro-t-butanol or octafluoropentanol; and saidalkanoic or haloalkanoic acid is formic acid, acetic acid,trifluoroacetic acid, propionic acid, tetrafluoropropionic acid orpentafluoropropionic acid.
 16. N,N'-Difluoro-1,4-diazoniabicyclo2.2.2!octane di(hydrogensulfate) of the formula: ##STR61##